Heat exchanger for continuous treatment of fluent material



Nov. 24, 1953 J. E. LASCHINGER 2,660,408 HEAT EXCHANGER FOR CONTINUOUS TREATMENT OF FLUENT MATERIAL Original Filed March 27, 1945 III - IELzs Cizllzgep I Patented Nov. 24, 1953 HEAT EXGHANGER FOR CONT-INUOUS? TRiEATM'ENTrI OE FLUENTEFMATERIAL ,Bramly; Jthannesbiug;

Union" oft South Africa" ovig'inal i-applicatione Marc1i:t227',-:1945;.\ Serial :Noa

58-5;11-3',-@now Patent No. 2,551,748, dated May 8, 1951. Divided and this sappj-icatiomApvilzfi,

'(ilaim's priority, applicatioir'Uiiion ofsoll-th Afi'icwssptember fiw 1944i 1' This:.-'app1i(:ati0fi is' :"a s division :of the fapplicars tion Serial Number" 585; 113'? filedi 011127: March" 1945'} .now- 'PatentNo; 2,55 1,748; patentediMayfl; 1951; l

Thistinventionlrela-tes to heat exehangers for continuously: effecting I heat exchange to o'r fron' a stream of material that is fluent'in bulls; such asliquids; or granular orparticulatef'solid matrial or" material in which the -ch aracteristi'es of a'li'quid aremorehighly developed? The obj ect-of the invention is -to approximate: closely to thecondition that every small elementof -the stream is equally exposed to the heat ex' changing influence for an'equal period of time: and thereby to produce a product of "a ho-m'oge neous character throughout; notwithstandingthat the material, for"instance"vermiculite-un dergoin-gjexpansion; is sensitive to both'temp'eiature'and time of heating. Theattainrn'ent' of thisobject is'promoted by su'bdividingfthe stream into small batches whichare passedthrough the heat exchangersuccessivelyiand in-'isol'atiorrfrom one anothena'nd .in equal time periods; andby; frequently agitating the contents of each" batch in a mannercalculatedtogiveall'its'smallele ments equal exposure to the heat" exchanging influence? Otherob jectsand advantages oftheinvention' will be apparent from the descriptiorrofan em bodiment of the invention, as applied tb the heating of material; which follows; andwhichis illustrated in the accompanying" drawings m which Figurelis an elevation, partly in section: of* a furnace according to theinvention;

Figure II is-"a perspectiveview of"the'internai' arrangement of the" furnace, part of thedr'um' wall being broken away;

Figure III'is a vertical section of"one-c0m-. partment taken on the line -III'III-of "Figure II Figure IV is a vertical section on the liner IV IV "of "Figure II showing the drum in a di'f-i frent rotational position;

Figure V is adetaii in perspective jofamodified' form of "partition: 7

Fig'ureVa is a further. detail in perspective. of? a'modifi'ed'form ofpartition; and; V

Figure 'VI is aseotiOn on the line..VI -VI i.of- EigureIIL.

m. the: drawings,- 2..-- indicates a drum. barreh positioned with-itsmm horizontal. The drum, is provi'dedswith circular treads: 4-rotatab1y su-p--- porteds. ona-rollers i." Thee drum= iSilOlSBrl'wBdsCOHQ 2:1 Tlie barreli of lthevdru-m is& enclosedqwithin raafu-renacescasingi 'l; .whi-chvmaya be; heated in anyrconvenientimanner; fon-instanceabygsfuel :burnt at 8e im the lower: part of: the? casing; Products? of, combustionipass avvayath-roughthe: 'chinineyi 9:.

Itewillbemnderstood thatwinnam apparatus? designed". to: extract heatifrom ithezmazteria'l be'mggi heated-Q thezburner 8 -Wou1d zbe-tormttediandfazsui-t; able coolingrsmeans would: be: substituted: for "it? suchifor instarrce as-xaacoldeair blast directed'ion'r to the drum or a coolin xcoilisurroundingi the? drum; ora' cooling medi um fed intm-the dru nr cavity;

The fluent material? to be subjected to treat ment with or without' an addition of powd'eredor granular fuel is -fedby*'a'- laimder I0 to ai batch making section' I I f of the dru'm atthe" feed endi I2 thereof; and the treatedmaterial isfgravi== tatio-nally' disharged ffo'r n the deliveryend 13 of the dru-mto ai receiver I4? I B 'repFeSents-a b'er 'of' "partitions-extending in planes-=materially I transverse to the axis 3 and: spaced i along: the length of the drum? and' defininga series of com partments i I6' I5; I6 2. I62", I I6"? I 63 of twh'ich:

theicompartmenttj 63 constitutesratheezbatch makain'gbompartmentfidentifi'ed as I I :in Figure: I; The partitionszmay bes parallelor: d'epartfromt parts i allelism where this may be desirableiowingitotthez nature-0f thermaterial being :treated or thesle'ind otltreatmenttbeingmarried out.

Thetpartitions. I 5. mawbefiat: a'SEShGWIYiII "Fig-I? ur'es :II and :II; or they; maybe :dishediastshown: ir'itEigureeVi In 5 either case: the central iareatof; each'=pa1"titioni I 53m'ay: beecut away at 'i I 1 so: that:

thesinterior 'offthe'e drum isiopen'z. An'. endcrview:

therefore: shows; am open; axial channelni extends ing-z completelmthrow:ehthe: drum", i which chan-' nel: is: useful: for: such purpo's'ess as: passing 01ft moisture: avaporisedgior fumes producedzwiiemther. material is heated; for visualiinspection .offthe: material; in? the :drum: if i desired. for the: introduction :of heatingjorcooling gas and f or. accomemed ating; a; radiating for: absorbing; element; or? forfpassage 0i; aastream s of gas-tor; liquid c for; the: removal of; products: of! decomposition: (ii ,e': gas: orr1iqu-id);:and.ito reduce thepartial p'ressur'ezofr such: reaction: products with: the object; of: iris-- creasingioracon troliing the; reaction rate;

Eachzcompartment I 6%,: I 6, I 61 I69; I 6%, I 6*? is: made; of: 3608 circumferentiai; extent; S03 tiiati thesbatcliesriofsmazterial'iaretkepttin:gravitational;, contaetzwithztheadrum :wall rfor-rlongxperiodssbea tweemtheicascadinggstepsrrwhilezthe materialist subjected to advantageous agitation by thecdraga 59mm, directmnv by' driving means 6; 557 ofitlie relativelyemoving drumzwallawhicmmay be corrugated circumferentially or longitudinally for structural reasons and/or to increase area and agitation.

The circumferential extent of each compartment is defined by cross partitions is that spring from the drum wall at l9 and extend in the axial direction between the boundary walls H 'of each compartment. The movement of each compartment is orbital in the sense that every portion of it moves orbitally. The phase displacement between successive compartments may be 180 as shown, or such other angle as may be selected as suitable. 1

The cross partitions 18 also walls IS, a scoop formation at the trailing end of each compartment. Batch transfer from one compartment to the next is efiected by the combination of the scoop formation with a plain hole 20 in each compartment wall 15; towards which hole the immediately adjacent portion 2! of the partition l8 is'tilted (as shown in Figure VI). As well as defining the circumferential beginning and end of each compartment, each cross partition I3 also performs the function of a mechanical barrier that maintains separation of a batch circumferentially in front of it, from a batch circumferentially behind it: and moreover allows the latter to gravitate into-the place of the former as the drum rotates. To assist in this operation it may be so curved as to be convex-z above when within the lower half of the drum and concave above when within the upper half of the drum. This is shown in Figure III where the cross partition I8a of compartment i is rising with its concave face 22 upward so that it acts as a scoop to contain and lift a batch a. The batch a has been raised to the position where it begins to pour through the hole Elia in the wall and into compartment 16 In there it is falling on the convex and. descending face 23 of the cross partition idb of the next compartment 18* and thereby being diverted into the pocket 24 formed by the conjunction of lab with the adjacent wall of the drum. In the pocket 24 the batch a is shielded from the next earlier batch b that is at the same moment lying at the bottom of the drum and under the concave face 22 of the cross partition.

Figure IV shows the two batches a and b in the compartment 16 after further rotation of the drum through about 30. Batch b is now being collected at the concave side of partition 18b preparatory to being raised to the position equivalent to that of batch a in Figure III. Batch a-is being released from the pocket 24 and spread out on the barrel of the drum, as batch b is in Figure III. To produce this sequence the holes are phased 180 apart; and each batch remains in a compartment during one and a half revolutions of the drum.

In order to give adequate lift it is desirable for the holes 26 to be near the drum barrel 2; which, on the other hand, opens the possibility of batches that are gravitationally lying in the compartments at opposite sides of their common partition i8, becoming mixed with one another when the hole 29 is at the low zone of its orbit, as is 2017 in Figure III. To overcome this, the cross partition i3 is continued at around the hole 20; to be convex below when the hole 20 is at the bottom of its orbit; and so that its terminal lip 26 is then and thereafter above the level of the material lying in the bottom of the drum.

; It is pointed out that the precise shape of the form, with thecross partitions I8 is selected in relation to the nature of the material being treated and the nature of the treatment itself, as well as to the speed of rotation of the drum and the varying dynamic consequences of rotation at different speeds on the fluidity of the material. Mechanical'considerations such as the provision of adequate heat-transfer area and stability of the cross-partition under heating, ease of manufacture, etc., must also be considered. In Figure Va the cross-partition difiers from that of the other figures in that it has a leading face 21 which is sloped towards the hole 20 to promote complete gravitational evacuation of the batch of material in the scoop formation through the hole 20.

In operation, material fed in a continuous stream into the compartment I6 by the launder ii] is batched by the compartment. Each batch in turn is gravitationally discharged into the compartment 16 through the hole 26; and so on. Isolation of the separate batches is ensured by the means discussed above, the advance of the series of batches being axial and the magnitude of each step of advance being the axial width of the compartments. On discharge from the last compartment each batch in turn is received by the receiver I4.

By keeping the batches small, the time periods of conveyance of their constituent small elements are approximated closely to that of the batches themselves. Each batch, after being received in a compartment, remains on the orbital bottom of the compartment substantially the entire rotation of the latter so that the batch is exposed to quiet heat transfer by contact with the outer wall; and so also that the relative movement between compartment and batch causes a mild agitation of the batch. The interruption of the relatively quiet heat transfer to or from the batches by a succession of falls causes all the small elements of each batch correspondingly to be subject to frequent changes of position in the batch, which is conducive to equalizing their exposure to the heat exchanging influence. At the same time, the importance of isolating the batches lies in preventing the small elements of the batches from escaping from the control that determines their time period and intensity of treatment in the heat exchanger.

I claim:

1. heat exchanger suitable for continuously treating material that is fluent in bulk, consisting of a rotatable drum the wall of which is impermeable to solids, means to adjust the temperature of the Wall to a temperature different from that of the surrounding atmosphere, a series of transverse partitions dividing the drum into a series of axially consecutive separate compartments, means to feed material into the first of the series of compartments and means to receive batches of material discharged from the last of the series or compartments, means defining a single scoop within each compartment, the scoop being adapted to lift material in the compartment during the upward movement of the scoop, and means defining a transfer hole in each partition opening out of the concavity of the scoop which is towards the feed end of the drum, each scoop being arranged for the material it is lifting to cascade gravitationally through the hole opening out from its concavity when the scoop has completed at least a portion of its upward movement, and each scoop being so circumferentially displaced from thescoop in the last preceding conipartment as to have started its upward movement before cascading of material into its compartment commences.

2. The exchanger claimed in claim I wherein each scoop includes one of said transverse partitions and a cross-partition in each compartment extending from the drum wall and forming a mechanical barrier to prevent the mingling of a batch of material circumferentially in front of the barrier with a, batch circumferentially behind the barrier.

3. The exchanger claimed in claim 2 in which the cross-partitions in successive compartments are phased 180 apart.

4. The exchanger claimed in claim 2 in which each cross-partition is curved to be convex upward when within the lower half of the drum, the convex side forming a pocket with the adjacent Wall of the drum, and the concave side delivering material to the transfer hole upon further rotation.

5. The exchanger claimed in claim 4 in which the ends of the cross-partitions are curved around the transfer openings to be convex below when the transfer openings are in their lowermost position and so that the terminal lip of each cross-partition is then and thereafter above the level of material lying in the bottom of the drum. 6. The exchanger claimed in claim 1 in which the transverse partitions are dished.

7. The exchanger claimed in claim 1 in which the part of the scoop adjacent the transfer opening is tilted towards the opening.

J. E. LASCHINGER.

References Cited in the file of this patent UNITED STATES PATENTS Laschinger May 8, 1951 

